| Abstract |
| The objective of this study is to investigate the reaction behavior of cobalt with molten zinc. Pure cobalt specimen was immersion tested in the molten pure zinc bath at 460℃, 490℃ and 520℃. For the understanding of degradation processes, specimens were analyzed with scanning electron microscope (SEM) and energy dispersive spectrum (EDS), and electrochemical stripping method. After immersion of Co in a molten zinc bath at 460℃ to 520℃ four kinds of Co-Zn intermetallic compound layers, β1, γ, γ1, and γ2 were formed on the Co matrix, which was confirmed by both microstructural observation and electrochemical stripping method. According to the Co-Zn binary phase diagram they were all the possible intermetallic compounds at the temperatures of experimental conditions. The relationship between weight loss after immersion tests and immersion time followed typical parabolic rate law. Rate controlling step for this reaction was analyzed as the inter-diffusion process of Co & Zn atoms through β1 compound layer and the activation energy for the process was csalculated to be 214.9 kJ/mole. |
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| Key Words |
| Co-binder, molten-Zn, immersion test in Zinc, parabolic rate Law, β1 phase, diffusion process |
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